DE2220538A1 - Liquid fuel burners - Google Patents

Description

PATENTANWÄLTE 8 MÜNCHEN 8O, MAUERK1RCHERSTR.

Dr. Berg Dipl.-Ing. Stapf, 8 Munich 80, Mauerkircherstroße 45

Lawyer file 22 370

Matsushita Electric Industrial Co. Ltd. Osaka / Japan

Liquid fuel burners

The present invention relates to a liquid fuel burner, and more particularly to a liquid fuel burner Fuel that uses ultrasonic waves to atomize the fuel.

Hot burners for liquid fuel, where an ultra-

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sound generator is used, the fuel forms a very thin film on a certain area of the vibrating surface, which with ultrasonic frequency in such a way vibrates that the fuel due to the ultrasonic vibrations of the vibrating surface in finely distributed Particles can be atomized. The well-known burners for liquid fuel in which ultrasonic wave generators Ren are used, all have the disadvantage that the kinetic energy of the atomized fuel particles is smaller than that of the fuel particles, which are atomized due to the air flow pressure, among other things, in such a way that they are atomized Fuel particles are not evenly distributed. That is, as the atomized fuel particles begin to fall down by gravity immediately after being pushed off the vibrating surface they create an overly enriched combustion or air / fuel mixture zone in the immediate vicinity Near the vibrating surface. However, this not only makes the ignition of such a highly enriched one Air / fuel mixture difficult, and combustion pulsation and jumping also occur or tear off the flames as the percentage of air in the air / fuel mixture is low. This will then the combustion efficiency is greatly reduced while the combustion noise increases. Among other things, the atomized fuel particles continue to see a lower kine ti

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Have energy, they are easily influenced by the flow of combustion air in such a way that they tend to become from the combustion zone to a low-combustion zone. This then wastes a significant amount of atomized fuel particles uselessly.

Therefore, in order to atomize a larger amount of fuel, the entrance to the ultrasonic wave generator must be enlarged will. If the input power continues to be greater than is the rated output, the heat consumption will be greater, which then leads to a shortening of the service life of the burner leads. In addition, in burners for liquid fuel using ultrasonic wave generators, the vibrations of the vibrator are transmitted to other components transmitted in such a way that the environment is severely annoyed by the resulting noise.

The invention therefore provides a liquid fuel burner which uses ultrasonic wave energy for atomization is used by fuels with high combustion efficiency. The object can continue to be designed in this way be that a liquid fuel burner produces less combustion noise.

The invention can also be designed so that a burner for liquid fuel due to the ultrasonic vibrations less mechanical vibrations generated.

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Finally, a liquid fuel burner according to the invention can have a high fuel atomization efficiency exhibit.

In burners for liquid fuel, the atomized fuel particles must be well mixed with the air and evenly in the air / fuel or combustion medium schung be distributed. According to the invention, therefore, the atomized fuel particles produced by the aerodynamic or directed air stream, enclosed by two vortex air streams in such a way that the atomized Fuel particles that tend to move away from the combustion zone to spread away, to converge towards the combustion zone. To continue due to the noise the ultrasonic vibrations to a minimum, are the exponential funnel and thus the Atomizing part held in such a way that the transmission of the vibrations of the funnel to other components is kept to a minimum is reduced. The materials for the atomization part can be chosen so that the highest Zer dusting efficiency is obtained.

The invention is described below on the basis of preferred exemplary embodiments explained in more detail, for which reference is made to the accompanying drawings. Show it:

Fig.l a longitudinal cross-section of a preferred embodiment

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form of the invention along the line I - I of Figure 2;

Fig. 2 is an end view from the left of the in Fig.l illustrated embodiment;

Fig. 3 is a partially sectioned side view to represent to η details of an exponential trient;

Fig. H is a right end view of the embodiment shown in Fig.l;

Fig. 5 to 7 graphic representations to explain the Liquid fuel burner according to the invention; and

Figures 8 and 9 are side and end views showing two Modifications for holding the exponential funnel of the burner according to the invention are shown.

In Fig.l an exponential funnel 1 has a base which is fixedly attached to a magnetostrictive vibrator 2, which in turn is coupled via lines 3 to an ultrasonic wave oscillator k. The funnel vibrates at an ultrasonic frequency when the magnetostrictive generator 2 vibrates. A cylindrical outer tube or housing 5 is arranged coaxially to the exponential funnel 1 and is fixedly attached on the left side to an annular end part 6 with a diverging or funnel-shaped part 6a, a curved wall part 6b and a radially extending flange part 6c. In the outer tube or housing 5 is coaxial with the funnel lein

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annular inner tube 7 arranged; between the outer and inner tubes 5 and 7, an outer mixing impeller 8 with a number of spiral blades 8a is arranged. Between the funnel 1 and the outer mixing impeller wheel 8 there is an inner mixing impeller 9, which is similar in structure to the outer mixing impeller 8. The exponential funnel 1 is supported on the outer tube or housing by means of a number of mounting arms 10, as will be described in detail later. Spark plugs 12, which are arranged in the outer tube or housing 5 and have spark discharge electrodes 13, extend through the outer mixing impeller 8 and are electrically coupled to a transformer 1h via high-voltage lines 11. A fuel regulator 16 is hydraulically connected via a fuel line 15 to a fuel injection port 17 which is formed in the center of the funnel 1 such that the fuel to an atomization surface 18 on the left side of the funnel 1 via the regulator 16, the fuel line 15 and the fuel injection port 17 is supplied.

The attachment of the funnel 1 will now be described in detail with reference to FIGS. 3 and k. In Fig. 3, the part labeled A in Fig.l is shown in detail. The funnel.1, which is caused to vibrate by the magnetostrictive vibrator 2, has nodes along its axis at which the amplitudes are zero; the fuel

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Line 15, which is connected to the fuel injection opening 17, is therefore introduced so that it extends radially into the funnel 1 at the junction. The funnel 1 is also supported at the node point. This means, . a number of arms 22 having holes 22a extend to the free ends at the same angle from the node position of the hopper 1, as the seeded in Fig. k to recognize and are connected to the mounting arms Io via vibration isolators 19 by means of screws 20 and nuts 21 _t as shown in Fig.3. Specifically, the vibration oscillator 19 is fitted into the hole 22a at the free end of the arm 22, and the screw 20 is inserted into the bore 19a of the isolator 19. The fastening arms 10 and the arms 22 are therefore arranged at a distance from one another by the vibration isolators 19. The lower parts of the fastening arms 10 can, for example, be firmly connected, for example welded, to the inner wall of the outer tube or housing 5. Since the arms 22 have a certain thickness, the vibrations of the funnel 1 are transmitted to the arms; but since the vibration oscillators between the arms 22 and the fastening arms 10 are inserted, the transmission of vibrations from the funnel 1 to the outer tube or housing 5, as shown in Figure 5, can be reduced considerably. In FIG. 5, the solid curve a shows the relationship between the sound pressure and the frequency when vibration oscillators are not used, while the dashed curve

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Tb represents the relationship when vibration oscillators 19 are used. From this it can be seen that according to the invention the sound pressure can be reduced to almost a quarter compared to burners without vibration oscillators.

In Pig.l, that of the oscillating surface 18 is controlled by the controller 16, the fuel line 15 and the fuel injection opening 17 via the atomization surface 18 to form a thin fuel film and then finely atomized. That is, the air is in the burner via a not shown, on the right side of the Burner in Pig.l arranged Yentilator supplied via an inlet opening 5a of the outer tube or housing 5. The supplied Air flows in the directions indicated by arrows P, Q, and R. That is, the air flows along the peripheral surface of the funnel 1 and between the funneli and the inner mixing vane wheel 9 therethrough, as indicated by arrow P; the air also flows through the interior Mixing impeller wheel 9, as indicated by arrow Q, and through openings 7a of the inner tube 7 and through the outer mixing impeller 8, as indicated by the arrow R. The air supplied then mixes with that at the atomizing surface 18 atomized fuel; the air / fuel or combustion mixture is generated between the electrodes 13 Spark ignited so that the flame and the combustion products through an opening 6 d of the end portion 6 in a combustion chamber not shown are ejected.

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With conventional burners, they are called ultrasonic generators to atomize the fuels used is the kinetic one The energy of the atomized particles is generally so small that a uniform distribution of the atomized PartitEl cannot be achieved. This is explained in detail below with reference to FIG. 3. The atomized, from the atomization surface 18 of the funnel 1 repelled fuel particles begin to fall, as in Figure 3 by a Circle B is indicated; the atomized, relatively large fuel particles want to move away from the axis of the Unfold funnel 1 * In some cases the atomized, relatively large fuel particles will be removed the combustion zone as indicated by circle C in Figure 3. The atomized and repelled from the funnel 1 Fuel particles are not evenly distributed along the axis of the funnel 1 and the required combustion mixing zone is not formed The combustion efficiency is also considerably reduced * Furthermore, the atomized fuel particles have quite a bit low speeds * so that they pass through the air stream are easily influenced * The burn therefore tends to pulsate and the flames "jump" or tear off this also results in a higher noise nuisance for the environment.

According to the invention, the atomized fuel particles can be distributed so that a higher combustion efficiency.

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degree can be achieved. That is, the atomized, from The fuel particles repelled from the atomization surface 18 of the funnel 1 are caused by the directed air flow carried away, which flows through the space 28 between the funnel 1 and the inner mixing impeller 9. Thereafter the fuel particles get through the from the inside Mixing impeller 9 swirled out flowing eddy air flow and mixed with this. This can then result in an optimal Air / fuel mixture can be formed in such a way that the combustion efficiency can be increased significantly and the pulsation in the combustion as well as jumping or tearing off the flames can be prevented; as a result, the combustion noise is then also at a minimum value degraded. To further prevent larger fuel particles from being removed from the combustion mixing zone and are thereby ineffective, is according to the invention coaxial and outside of the inner mixed-wing impeller 9, the outer misehousing impeller 8 arranged so that the combustion mixture, which is mainly by the aligned air flow flowing through the gap 28 and through the iiinere Turbulent air flow flowing through the impeller 9 is formed, from which exiting from the outer mixing impeller 8 Vortex airflow can be enclosed. The fuel particles emerging from the vortex of the air / fuel mixture removed ^ can then be returned to the air / fuel mixing zone. In particular, it flows from the outside Mixing impeller 8 exiting vortex air flow along the inner surface of the end part 6 and is then by means of the

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radially extending flange part 6c converging against the

/of
Axis burner is directed so that the fuel particles that have moved away from the combustion mixing zone can be returned and concentrated in the mixing zone. By means of the diverging wall part 6a of the end part 6, the speed of the vortex air flow emerging from the outer mixing impeller 9 can be adjusted so that the vortex of the combustion mixture does not spread unnecessarily far from the vortex air flow emerging from the outer mixing impeller 8, and that the noise as a result of the vortex air flow can be reduced to a minimum value from the outer mixing impeller.

In general, the burners that use ultrasonic generators are used to atomize the fuels, not all liquid fuels are used; the atomization the liquid fuel depends on the properties the liquid fuels used and the material that makes up the atomizing surface 18 of the funnel 1 forms. In particular, the atomization is mainly due to the surface tension of the fuels and the properties the material of the atomization surface 18 is influenced. The effects of the surface tension of the liquid Fuels during the atomization time have therefore been carefully studied by the inventor. For example became the surface tension of kerosene, the surface tension of which is 26 dynes / cm, by adding

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a mixture of water and isopropyl alcohol changed; the atomization time of kerosene with different surface tensions was measured. The experiments were carried out so carefully that the kerosene while it was atomizing will not flow. The test results are shown in Fig. 6 shown. The tests have shown that when the atomization surface 18 is made of aluminum, the atomization is much greater than if the surface is made of other Materials is made. The curve a shows the atomization time when an atomization surface 18 from Aluminum is used; curve b shows the atomization time, xirenn the atomization surface is made of an aluminum-coated, low carbon steel or mild steel is made; curve c finally gives the atomization time again when the atomizing surface is made of low carbon steel or mild steel. From Fig.6 is to see that with an aluminum atomizing surface, the atomization is very much improved and almost independent on the surface tension of the fuels used. If the atomization surface is made of low-carbon steel the atomization time is longer and is made strong by the surface tension that affects liquid fuels.

In Fig.7 is the relationship between the electrical input power, which is plotted on the abscissa, and the atomization speed, that is, the amount atomized Fuel per minute, which is plotted on the ordinate,

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shown. From Figure 7 it can be seen that if a sputtering surface made of aluminum or an atomizing surface coated with aluminum is used, the amount of fuel atomized per unit electrical input power is much larger. This means that the Loss of heat due to the vibrations of the ultrasonic generator is less, so that the service life of the burner is greater and the combustion noise can be reduced to a minimum. So it is very important that the Atomization surface 18 made of a material or is coated with a material whose properties facilitate the atomization of the liquid fuels.

A first modification to the Attachment of the funnel 1 described. The fastening arms IO are bifurcated, and the arms 22 of the funnel 1 are between the fastening arms 10 are supported via vibration isolators 19a, since the forked arms of the fastening arms 10 can be firmly tightened by means of adjusting screws 23, the arms 22 of the funnel 1 are firmly in the predetermined Location held.

A second modification for attaching the funnel 1 is described with reference to FIG. Along the circle of the funnel 1, which corresponds to the oscillation nodes, are a number of blind or. Blind bores 23 formed; the pointed ends of the fastening arms 2k,

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25 and 26 are fitted into the Bohruig en 23 ^, whereby the funnel 1 is supported and held in the correct position. In order to facilitate the attachment and removal of the funnel, one of the fastening arms can be a screw 2k which is screwed into an internally threaded part 27 which is permanently installed on the outer tube or housing 5 and is formed therein in such a way that when the Screw is tightened or loosened, it can move towards the funnel or away from it, where the tapered end of the screw 24t fits into the bore 23 or is released from it. The second vorbe written modification has the advantage that, since the

/in
Funnel 1 of the given position is supported and held at the junction by fastening arms, among other things, vibrations are almost not transmitted to the outer tube or housing 5 at all, even if vibration isolators are not used.

The invention thus provides a burner for liquid fuel that has a fuel atomization surface or has a region which is at the free end of an exponential funnel is formed, the base of which is firmly attached to a vibrator, which is attached to an ultrasonic generator is coupled, and which is attached so that its vibrations are not to a funnel enclosing Outer tube or housing are transferred. An inner misoh impeller is coaxially tuid outside the focal

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Stoffzerstäuljungsf pool of the funnel at a distance from this arranged; next Mn is an outer mixing impeller coaxial and outside the hall) of the inner mixing impeller. At the discharge end of the outer tube or housing is an end piece with a diverging wall part, a curved wall part and a radially inwardly extending flange portion is formed whereby the stream of atomized fuel particles is controlled.

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Claims (10)

Claims Burner for liquid fuel, characterized by an ultrasonic generator (4), by a funnel (1), one side of which is attached to a vibrator (2) which is coupled to the ultrasonic generator (4), and the other side of which is an atomizing surface (18 ) for liquid fuel, through an outer tube (6) coaxially surrounding the vibrator (2) and the funnel (1), through devices (10, 19, 22) for holding the funnel (1) in the outer tube (6) Devices (15, 16, 17) for supplying the fuel to the atomization surface (18) of the funnel (1), by devices (8, 9) ^T arranged coaxially and outside the atomization surface (17) for aligning and swirling atomized fuel particles, and by devices (6, 6a, 6b, 6c) to decrease the velocities of the swirled, atomized fuel particles and to converge the stream of atomized fuel particles. 2. Burner according to claim 1, characterized in that that the devices for swirling the atomized fuel particles are arranged coaxially to the funnel outer and inner mixing impeller (8, 9) have that the outer and inner mixing impeller (8, 9) a number t_n the same angle arranged helical blades 2 nights 9 8 A 6/0 8 7 U - 17 - gel (8a) for swirling the stream of atomized fuel particles have, and that for directing the stream of atomized fuel particles, an annular space (28) between the peripheral surface of the funnel (l) and the inside Mixing impeller (9) is formed. 3. Burner according to Anspruah 1, characterized in that the device for reducing the Speed of the atomized fuel particles an end part attached to the discharge side of the outer tube (6) with a diverging wall part (6aV, a curved wall part (6b) and a radially inwardly extending one Has paddling part (6c). k. Burner according to Claim 1, characterized in that the funnel (1) is carried and held in a specific position at the point of the vibration nodes by holding devices (10, 19, 22). 5. Burner according to claim 1, characterized in that the atomizing surface (18) of the funnel (l) is made of a material whose adhesion * power is low compared to fuels. 6. Burner according to claim 1, characterized in that the atomizing surface (18) of the funnel (l) is coated with a material, the adhesion of which 209846 / 087Λ - 18 - sion force compared to fuels is low. 7. Burner according to claim 4, characterized in that the holding devices have vibration isolators (19, 19a) such that the transmission of vibrations from one side to the other of the holding- . Before
facilities (10, 22J is separated. 8. Burner according to claim 4, characterized in that the ^ old device a number of the point of the vibration nodes has formed blind or blind holes (23) and a number of supports (25, 26), whose front ends are pointed and a substantially point-like contact with the funnel (1) in the blind or Form blind holes (23). 9. Burner according to claim 5, characterized in that the material of the atomization surface (18) Aluminum is. 10. Burner according to claim 6, characterized in that the material for coating the The atomizing surface (18) is aluminum. 209846/0874 , 43. Le. first page